Internal combustion engines, its mechanisms, refinements and iterations are used in a variety of moving and non-moving vehicles or housings. Today, for example, internal combustion engines are found in terrestrial passenger and industrial vehicles, marine, stationary, and aerospace applications.
Engines, for example vehicle engines, are being downsized and boosted, which is reducing the available vacuum from the engine. This vacuum has many potential uses, including use by the vehicle brake booster to reduce the brake actuation force required from the operator.
One solution to this vacuum shortfall is to install a vacuum pump. Vacuum pumps, however, have a significant cost and weight penalty to the engine, their electric power consumption can require additional alternator capacity, and their inefficiency can hinder fuel economy improvement actions.
Another solution is an aspirator that generates vacuum by creating an engine air flow path that is parallel to the throttle, referred to as an intake leak. This leak flow passes through a Venturi that generates a suction vacuum. To limit the bypass of the engine throttle, it has been known to place a flow control device in the motive flow path. One way to regulate the amount of flow is to utilize a sophisticated variable flow rate control device, which requires some means to control the flow resistance. This solution is complicated and expensive.
There is a need to continue to improve the efficiency, power, and control within engine systems utilizing simpler and less expensive techniques, including the generation of vacuum for various applications such as brake boost.